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Versions: 00 01 02 03 04 05 06 RFC 6313

     IPFIX Working Group                                    B. Claise
     Internet-Draft                                     G. Dhandapani
     Intended Status: Standards Track                        S. Yates
     Expires: January 10, 2011                              P. Aitken
                                                  Cisco Systems, Inc.
                                                        July 10, 2010
 
                        Export of Structured Data in IPFIX
                     draft-ietf-ipfix-structured-data-02.txt
 
 
     Status of this Memo
 
        This Internet-Draft is submitted to IETF in full conformance
        with the provisions of BCP 78 and BCP 79.
 
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        This Internet-Draft will expire on September, 2010.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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     Copyright Notice
 
        Copyright (c) 2010 IETF Trust and the persons identified as the
        document authors.  All rights reserved.
 
        This document is subject to BCP 78 and the IETF Trust's Legal
        Provisions Relating to IETF Documents
        (http://trustee.ietf.org/license-info) in effect on the date of
        publication of this document.  Please review these documents
        carefully, as they describe your rights and restrictions with
        respect to this document.  Code Components extracted from this
        document must include Simplified BSD License text as described
        in Section 4.e of the Trust Legal Provisions and are provided
        without warranty as described in the Simplified BSD License.
 
 
 
     Abstract
 
        This document specifies an extension to the IP Flow Information
        eXport (IPFIX) protocol specification in [RFC5101] and the IPFIX
        information model specified in [RFC5102] to support hierarchical
        structured data and lists (sequences) of Information Elements in
        data records.  This extension allows definition of complex data
        structures such as variable-length lists and specification of
        hierarchical containment relationships between Templates.
 
 
     Conventions used in this document
 
        The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
        NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
        "OPTIONAL" in this document are to be interpreted as described
        in RFC 2119 [RFC2119].
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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     Table of Contents
 
 
        1. Overview................................................... 7
           1.1. IPFIX Documents Overview.............................. 7
           1.2. Relationship between IPFIX and PSAMP.................. 7
        2. Terminology................................................ 8
           2.1. New Terminology....................................... 8
        3. Introduction............................................... 8
           3.1. The IPFIX Track....................................... 9
           3.2. The IPFIX Limitations................................ 10
           3.3. The Proposal......................................... 12
        4. Linkage with the Information Model........................ 13
           4.1. New Abstract Data Types.............................. 13
              4.1.1. basicList....................................... 13
              4.1.2. subTemplateList................................. 14
              4.1.3. subTemplateMultiList............................ 14
           4.2. New Data Type Semantic............................... 14
              4.2.1. List............................................ 14
           4.3. New Information Elements............................. 14
              4.3.1. basicList....................................... 14
              4.3.2. subTemplateList................................. 15
              4.3.3. subTemplateMultiList............................ 15
           4.4. New Structured Data Type Semantics................... 15
              4.4.1. undefined....................................... 15
              4.4.2. noneOf.......................................... 15
              4.4.3. exactlyOneOf.................................... 16
              4.4.4. oneOrMoreOf..................................... 17
              4.4.5. allOf........................................... 17
              4.4.6. ordered......................................... 18
           4.5. Encoding of IPFIX Data Types......................... 18
              4.5.1. basicList....................................... 18
              4.5.2. subTemplateList................................. 21
              4.5.3. subTemplateMultiList............................ 22
        5. Structured Data Format.................................... 25
           5.1. Length Encoding Considerations....................... 25
           5.2. Recursive Structured Data............................ 26
           5.3. Structured Data Information Elements Applicability in
           Options Template Sets..................................... 26
           5.4. Usage Guidelines for Equivalent Data Representations. 27
           5.5. Padding.............................................. 28
           5.6. Semantic............................................. 28
        6. Template Management....................................... 32
        7. The Collecting Process's Side............................. 33
        8. Structured Data Encoding Examples......................... 33
           8.1. Encoding a Multicast Data Record with BasicList...... 34
           8.2. Encoding a Load-balanced Data Record with a BasicList 36
 
 
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           8.3. Encoding subTemplateList............................. 37
           8.4. Encoding subTemplateMultiList........................ 40
           8.5. Encoding an Options Template Set using Structured Data44
        9. Relationship with the Other IFPIX Documents............... 48
           9.1. Relationship with Reducing Redundancy................ 48
              9.1.1. Encoding Structured Data Element using Common
              Properties............................................. 49
              9.1.2. Encoding Common Properties elements With Structured
              Data Element........................................... 49
           9.2. Relationship with Guidelines for IPFIX Testing....... 51
           9.3. Relationship with Bidirectional Flow Export.......... 52
           9.4. Relationship with IPFIX Mediation Function........... 52
        10. IANA Considerations...................................... 53
           10.1. New Abstract Data Types............................. 53
              10.1.1. basicList...................................... 53
              10.1.2. subTemplateList................................ 53
              10.1.3. subTemplateMultiList........................... 53
           10.2. New Data Type Semantics............................. 54
              10.2.1. list........................................... 54
           10.3. New Information Elements............................ 54
              10.3.1. basicList...................................... 54
              10.3.2. subTemplateList................................ 54
              10.3.3. subTemplateMultiList........................... 55
           10.4. New Structured Data Semantics....................... 55
              10.4.1. undefined...................................... 55
              10.4.2. noneOf......................................... 55
              10.4.3. exactlyOneOf................................... 56
              10.4.4. oneOrMoreOf.................................... 56
              10.4.5. allOf.......................................... 56
              10.4.6. ordered........................................ 56
        11. Security Considerations.................................. 56
        12. References............................................... 56
           12.1. Normative References................................ 56
           12.2. Informative References.............................. 57
        13. Acknowledgement.......................................... 58
        14. Authors' Addresses....................................... 58
        Appendix A.  Additions to XML Specification of IPFIX
        Information Elements and Abstract Data Types................. 59
        Appendix B.  Example of Biflow Encoding using Structured
        Data Information Elements.................................... 64
        Appendix C.  Encoding IPS Alert using Structured Data
        Information Elements......................................... 67
 
 
 
 
 
 
 
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     Table of Figures
 
     Figure A: basicList Information Element Encoding.............. 19
     Figure B: basicList Encoding with Enterprise Number........... 20
     Figure C: Variable-Length basicList Information Element Encoding
        (Length < 255 octets) ..................................... 20
     Figure D: Variable-Length basicList Information Element Encoding
        (Length 0 to 65535 octets) ................................ 20
     Figure E: subTemplateList Encoding............................ 21
     Figure F: Variable-Length subTemplateList Information Element
        Encoding (Length < 255 octets) ............................ 22
     Figure G: Variable-Length subTemplateList Information Element
        Encoding (Length 0 to 65535 octets) ....................... 22
     Figure H: subTemplateMultiList Encoding....................... 24
     Figure I: Variable-Length subTemplateMultiList Information Element
        Encoding (Length < 255 octets) ............................ 25
     Figure J: Variable-Length subTemplateMultiList Information Element
        Encoding (Length 0 to 65535 octets) ....................... 25
     Figure K: Encoding basicList, Template Record................. 34
     Figure L: Encoding basicList, Data Record, Semantic allOf..... 35
     Figure M: Encoding basicList, Data Record with Variable-Length
        Elements, Semantic allOf .................................. 36
     Figure N: Encoding basicList, Data Record, Semantic ExactlyOneOf37
     Figure O: Encoding subTemplateList, Template for One-Way Delay
        Metrics ................................................... 38
     Figure P: Encoding subTemplateList, Template Record........... 38
     Figure Q: Encoding subTemplateList, Data Set.................. 39
     Figure R: Encoding subTemplateMultiList, Template for
        Classification Attributes ................................. 42
     Figure S: Encoding subTemplateMultiList, Template for Sampling
        Attributes ................................................ 43
     Figure T: Encoding subTemplateMultiList, Template for Flow Record
         .......................................................... 43
     Figure U: Encoding subTemplateMultiList, Data Set............. 44
     Figure V: PSAMP SSRI to be encoded............................ 46
     Figure W: Options Template Record for PSAMP SSRI using
        subTemplateMultiList ...................................... 46
     Figure X: PSAMP SSRI, Template Record for interface........... 47
     Figure Y: PSAMP SSRI, Template Record for linecard............ 47
     Figure Z: PSAMP SSRI, Template Record for linecard and interface47
     Figure ZA: Example of a PSAMP SSRI Data Record, Encoded using a
        subTemplateMultiList ...................................... 48
     Figure ZB: Common and Specific Properties Exported Together
        [RFC5473] ................................................. 49
     Figure ZC: Common and Specific Properties Exported Separately
        according to [RFC5473] .................................... 50
 
 
 
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     Figure ZD: Common and Specific Properties Exported with Structured
        Data Information Element .................................. 50
     Figure B0: Using a subTemplateList to represent a Biflow...... 64
     Figure B1: Template for the Biflow Fields..................... 65
     Figure B2: Template for the Key Fields........................ 65
     Figure B3: Biflow Data Set Encoded using Structured Data...... 66
     Figure C0: Encoding IPS Alert, Template for Target............ 69
     Figure C1: Encoding IPS Alert, Template for Attacker.......... 69
     Figure C2: Encoding IPS Alert, Template for Participant....... 70
     Figure C3: Encoding IPS Alert, Template for IPS Alert......... 70
     Figure C4: Encoding IPS Alert, Data Set....................... 72
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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     1. Overview
 
     1.1. IPFIX Documents Overview
 
      The IPFIX Protocol [RFC5101] provides network administrators with
      access to IP Flow information.
 
      The architecture for the export of measured IP Flow information
      out of an IPFIX Exporting Process to a Collecting Process is
      defined in the IPFIX Architecture [RFC5470], per the requirements
      defined in RFC 3917 [RFC3917].
 
      The IPFIX Architecture [RFC5470] specifies how IPFIX Data Records
      and Templates are carried via a congestion-aware transport
      protocol from IPFIX Exporting Processes to IPFIX Collecting
      Processes.
 
      IPFIX has a formal description of IPFIX Information Elements,
      their name, type and additional semantic information, as specified
      in the IPFIX information model [RFC5102].
 
      In order to gain a level of confidence in the IPFIX
      implementation, probe the conformity and robustness, and allow
      interoperability, the Guidelines for IPFIX Testing [RFC5471]
      presents a list of tests for implementers of compliant Exporting
      Processes and Collecting Processes.
 
      The Bidirectional Flow Export [RFC5103] specifies a method for
      exporting bidirectional flow (biflow) information using the IP
      Flow Information Export (IPFIX) protocol, representing each Biflow
      using a single Flow Record.
 
      The "Reducing Redundancy in IP Flow Information Export (IPFIX) and
      Packet Sampling (PSAMP) Reports" [RFC5473] specifies a bandwidth
      saving method for exporting Flow or packet information, by
      separating information common to several Flow Records from
      information specific to an individual Flow Record: common Flow
      information is exported only once.
 
 
     1.2. Relationship between IPFIX and PSAMP
 
      The specification in this document applies to the IPFIX protocol
      specifications [RFC5101].  All specifications from [RFC5101] apply
      unless specified otherwise in this document.
 
 
 
 
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      The Packet Sampling (PSAMP) protocol [RFC5476] specifies the
      export of packet information from a PSAMP Exporting Process to a
      PSAMP Collecting Process.  Like IPFIX, PSAMP has a formal
      description of its information elements, their name, type and
      additional semantic information.  The PSAMP information model is
      defined in [RFC5477].
 
      As the PSAMP protocol specifications [RFC5476] are based on the
      IPFIX protocol specifications, the specifications in this document
      are also valid for the PSAMP protocol.
 
      Indeed, the major difference between IPFIX and PSAMP is that the
      IPFIX protocol exports Flow Records while the PSAMP protocol
      exports Packet Reports.  From a pure export point of view, IPFIX
      will not distinguish a Flow Record composed of several packets
      aggregated together, from a Flow Record composed of a single
      packet.  So the PSAMP export can be seen as a special IPFIX Flow
      Record containing information about a single packet.
 
 
     2. Terminology
 
      IPFIX-specific terminology used in this document is defined in
      Section 2 of the IPFIX protocol specification [RFC5101] and
      Section 3 of PSAMP protocol specification [RFC5476].  As in
      [RFC5101], these IPFIX-specific terms have the first letter of a
      word capitalized when used in this document.
 
 
     2.1. New Terminology
 
      Structured Data Information Element
 
          One of the Information Elements supporting structured data,
          i.e., the basicList, subTemplateList, or subTemplateMultiList
          Information Elements specified in section 4.3.
 
 
     3. Introduction
 
      While collecting the interface counters every five minutes has
      proven to be useful in the past, more and more granular
      information is required from network elements for a series of
      applications: performance assurance, capacity planning, security,
      billing, or simply monitoring.  However, the amount of information
      has become so important that, when dealing with highly granular
      information such as Flow information, a push mechanism (as opposed
 
 
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      to a pull mechanism, such as SNMP) is the only solution for
      routers whose primary function is to route packets.  Indeed,
      polling short-live Flows via SNMP is not an option: high end
      routers can support hundreds of thousands of Flows simultaneously.
      Furthermore, in order to reduce the export bandwidth requirements,
      the network elements have to integrate mediation functions to
      aggregate the collected information, both in space and time.
 
      Typically, it would be beneficial if access routers could export
      Flow Records, composed of the counters before and after the WAN
      optimization mechanism, instead of exporting two Flow Records with
      identical tuple information.
 
      In terms of aggregation in time, let us imagine that, for
      performance assurance, the network management application must
      receive the performance metrics associated with a specific flow,
      every millisecond.  Since the performance metrics will be
      constantly changing, there is a new dimension to the Flow
      definition: we are not dealing anymore with a single Flow lasting
      a few seconds or a few minutes, but with a multitude of one
      millisecond sub flows for which the performance metrics are
      reported.
 
      Which current protocol is suitable for these requirements: push
      mechanism, highly granular information, and huge number of similar
      records? IPFIX, as specified in RFC5101 would give part of the
      solution.
 
 
     3.1. The IPFIX Track
 
      The IPFIX working group has specified a protocol to export IP Flow
      information [RFC5101].  This protocol is designed to export
      information about IP traffic Flows and related measurement data,
      where a Flow is defined by a set of key attributes (e.g. source
      and destination IP address, source and destination port, etc.).
 
      The IPFIX protocol specification [RFC5101] specifies that IP
      traffic measurements for Flows are exported using a TLV (type,
      length, value) format.  The information is exported using a
      Template Record that is sent once to export the {type, length}
      pairs that define the data format for the Information Elements in
      a Flow.  The Data Records specify values for each Flow.
 
      Based on the Requirements for IP Flow Information Export (IPFIX)
      [RFC3917], the IPFIX protocol has been optimized to export Flow
      related information.  However, thanks to its Template mechanism,
 
 
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      the IPFIX protocol can export any type of information, as long as
      the relevant Information Element is specified in the IPFIX
      information model [RFC5102], registered with IANA [IANA-IPFIX], or
      specified as an enterprise-specific Information Element.  For each
      Information Element, the IPFIX information model [RFC5102] defines
      a numeric identifier, an abstract data type, an encoding mechanism
      for the data type, and any semantic constraints.  Only basic,
      single-valued data types, e.g., numbers, strings, and network
      addresses are currently supported.
 
 
     3.2. The IPFIX Limitations
 
      The IPFIX protocol specification [RFC5101] does not support the
      encoding of hierarchical structured data and arbitrary-length
      lists (sequences) of Information Elements as fields within a
      Template Record.  As it is currently specified, a Data Record is a
      "flat" list of single-valued attributes.  However, it is a common
      data modeling requirement to compose complex hierarchies of data
      types, with multiple occurrences, e.g., 0..* cardinality allowed
      for instances of each Information Element in the hierarchy.
 
      A typical example is the MPLS label stack entries model.  An early
      NetFlow implementation used two Information Elements to represent
      the MPLS label stack entry: a "label stack entry position"
      followed by a "label stack value".  However, several drawbacks
      were discovered.  Firstly, the Information Elements in the
      Template Record had to be imposed so that the position would
      always precede the value.  However, some encoding optimizations
      are based on the permutation of Information Element order.
      Secondly, a new semantic intelligence, not described in the
      information model, had to be hardcoded in the Collecting Process:
      the label value at the position "X" in the stack is contained in
      the "label stack value" Information Element following by a "label
      stack entry position" Information Element containing the value
      "X".  Therefore, this model was abandoned.
 
      The selected solution in the IPFIX information model [RFC5102] is
      a long series of Information Elements: mplsTopLabelStackSection,
      mplsLabelStackSection2, mplsLabelStackSection3,
      mplsLabelStackSection4, mplsLabelStackSection5,
      mplsLabelStackSection6, mplsLabelStackSection7,
      mplsLabelStackSection8, mplsLabelStackSection9,
      mplsLabelStackSection10.  While this model removes any ambiguity,
      it overloads the IPFIX information model with repetitive
      information.  Furthermore, if mplsLabelStackSection11 is required,
      IANA [IANA-IPFIX] will not be able to assign the new Information
 
 
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      Element next to the other ones in the registry, which might cause
      some confusion.
 
      Clearly a real structured data type composed of ("label stack
      entry position", "label stack value") pairs, potentially repeated
      multiple times in Flow Records would be more efficient from an
      information model point of view.
 
      Some more examples enter the same category: how to encode the list
      of output interfaces in a multicast Flow, how to encode the list
      of BGP Autonomous Systems (AS) in a BGP Flow, how to encode the
      BGP communities in a BGP Flow, etc?
 
      The one-way delay passive measurement, which is described in the
      IPFIX Applicability [RFC5472], is yet another example that would
      benefit from a structured data encoding.  Assuming synchronized
      clocks, the Collector can deduce the one-way delay from the
      following two Information Elements, collected from two different
      Observation Points:
          - Packet arrival time: observationTimeMicroseconds [RFC5477]
          - Packet ID: digestHashValue [RFC5477]
      Ideally, the measurement at the second Observation Point should
      start a little bit later than at the first Observation Point,
      allowing the packets to arrive at the destination.  In practice,
      this implies that many pairs of (observationTimeMicroseconds,
      digestHashValue) must be exported for each Observation Point, even
      if some optimization based on Hash-Based Filtering [RFC5475] is
      used.  Instead of exporting repetitive information as part of
      every single Flow Record (for example, the 5 tuple), an optimized
      flow record composed of a structured data type such as the
      following would save a lot of bandwidth:
 
          5 tuple
                    { observationTimeMicroseconds 1, digestHashValue 1 }
                    { observationTimeMicroseconds 2, digestHashValue 2 }
                    { observationTimeMicroseconds 3, digestHashValue 3 }
                    { ...  , ... }
 
      As a last example, here is a more complex case of hierarchical
      structured data encoding.  Consider the example scenario of an IPS
      (Intrusion Prevention System) alert data structure containing
      multiple participants, where each participant contains multiple
      attackers and multiple targets, with each target potentially
      composed of multiple applications, as depicted below:
 
          alert
 
 
 
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              signatureId
              protocolIdentifier
              riskRating
              participant 1
                  attacker 1
                      sourceIPv4Address
                      applicationId
                  ...
                  attacker N
                      sourceIPv4Address
                      applicationId
                  target 1
                      destinationIPv4Address
                      applicationId 1
                      ...
                      applicationId n
                  ...
                  target N
                      destinationIPv4Address
                      applicationId 1
                      ...
                      applicationId n
              participant 2
                  ...
 
      To export this information in IPFIX, the data would need to be
      flattened (thus losing the hierarchical relationships) and a new
      IPFIX Template created for each alert, according to the number of
      applicationID elements in each target, the number of targets and
      attackers in each participant, and the number of participants in
      each alert.  Clearly each Template will be unique to each alert,
      and a large amount of CPU, memory and export bandwidth will be
      wasted creating, exporting, maintaining, and withdrawing the
      Templates.  See Appendix C for a specific example related to this
      case study.
 
 
     3.3. The Proposal
 
      This document specifies an IPFIX extension to support hierarchical
      structured data and variable-length lists by defining three new
      Information Elements and three corresponding new abstract data
      types called basicList, subTemplateList, and subTemplateMultiList.
 
 
 
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      These are defined in Section 4.1.  The three list Information
      Elements carry some semantic information so that the Collecting
      Process can understand the relationship between the different list
      elements.
 
      It is important to note that whereas the Information Elements and
      abstract data types defined in the IPFIX information model
      [RFC5102] represent single values, these new abstract data types
      are structural in nature and primarily contain references to other
      Information Elements and to Templates.  By referencing other
      Information Elements and Templates from an Information Element's
      data content, it is possible to define complex data structures
      such as variable-length lists and to specify hierarchical
      containment relationships between Templates.  Therefore, this
      document prefers the more generic "Data Record" term to the "Flow
      Record" term.
 
      This document specifies three new abstract data types, which are
      basic blocks to represent structured data.  However, this document
      does not comment on all possible combinations of basicList,
      subTemplateList, and subTemplateMultiList.  Neither, does it limit
      the possible combinations.
 
     4. Linkage with the Information Model
 
      As in the IPFIX Protocol specification [RFC5101], the new
      Information Elements specified in Section 4.3. below MUST be sent
      in canonical format in network-byte order (also known as the big-
      endian byte ordering).
 
 
     4.1. New Abstract Data Types
 
      This document specifies three new abstract data types, as
      described below.
 
 
     4.1.1. basicList
 
      The type "basicList" represents a list of zero or more instances
      of any single Information Element, primarily used for single-
      valued data types.  For example, a list of port numbers, a list of
      interface indexes, a list of AS in a BGP AS-PATH, etc.
 
 
 
 
 
 
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     4.1.2. subTemplateList
 
      The type "subTemplateList" represents a list of zero or more
      instances of a structured data type, where the data type of each
      list element is the same and corresponds with a single Template
      Record.  For example, a structured data type composed of multiple
      pairs of ("MPLS label stack entry position", "MPLS label stack
      value"), a structured data type composed of performance metrics, a
      structured data type composed of multiple pairs of IP address,
      etc.
 
 
     4.1.3. subTemplateMultiList
 
      The type "subTemplateMultiList" represents a list of zero or more
      instances of a structured data type, where the data type of each
      list element can be different and corresponds with different
      template definitions.  For example, a structured data type
      composed of multiple access-list entries, where entries can be
      composed of different criteria types.
 
 
     4.2. New Data Type Semantic
 
      This document specifies a new data type semantic, as described
      below.
 
 
     4.2.1. List
 
      A list represents an arbitrary-length sequence of zero or more
      structured data elements, either composed of regular Information
      Elements or composed of data conforming to a Template Record.
 
     4.3. New Information Elements
 
      This document specifies three new Information Elements, as
      described below.
 
 
     4.3.1. basicList
 
      A basicList specifies a generic Information Element with a
      basicList abstract data type as defined in Section 4.1.1. and list
      semantics as defined in Section 4.2.1.  For example, a list of
      port numbers, a list of interface indexes, etc.
 
 
 
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      EDITOR'S NOTE: while waiting for IANA [IANA-IPFIX] to assign this
      new Information Element identifier, the value XXX is used in all
      the examples and in the XML in Appendix A.
 
     4.3.2. subTemplateList
 
      A subTemplateList specifies a generic Information Element with a
      subTemplateList abstract data type as defined in Section 4.1.2.
      and list semantics as defined in Section 4.2.1.
 
      EDITOR'S NOTE: while waiting for IANA [IANA-IPFIX] to assign this
      new Information Element identifier, the value YYY is used in all
      the examples.
 
 
     4.3.3. subTemplateMultiList
 
      A subTemplateMultiList specifies a generic Information Element
      with a subTemplateMultiList abstract data type as defined in
      Section 4.1.3. and list semantics as defined in Section 4.2.1.
 
      EDITOR'S NOTE: while waiting for IANA [IANA-IPFIX] to assign this
      new Information Element identifier, the value ZZZ is used in all
      the examples.
 
     4.4. New Structured Data Type Semantics
 
     Structured Data type semantics are provided in order to express
     the relationship among multiple list elements in a Structured Data
     Information Element.  These Structured Data type semantics require
     a new IPFIX subregistry, as specified in the "IANA Considerations"
     section.  The semantics are specified in the next following
     sections.
 
     4.4.1. undefined
 
     The "undefined" Structured Data type semantic specifies that the
     semantic of list elements is not specified, and that, if a
     semantic exists, then it is up to the Collecting Process to draw
     its own conclusions.  The "undefined" structured data type
     semantic is the default Structured Data type semantic.
 
     4.4.2. noneOf
 
     The "noneOf" Structured Data type semantic specifies that none of
     the elements are actual properties of the Data Record.
 
 
 
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     For example, a mediator might want to report to a Collector that a
     specific Flow is suspicious, but that it checked already that this
     Flow does not belong to the attack type 1, attack type 2, and
     attack type 3.  So this Flow might need some further inspection.
     In such a case, the mediator would report the Flow Record with a
     basicList composed of (attack type 1, attack type 2, attack type
     3) and the respective Structured Data type semantic of "noneOf".
 
     Another example is a router that monitors some specific BGP AS-
     PATHs and reports if a Flow belongs to any of them.  If the router
     wants to export that a Flow does not belong to any of the
     monitored BGP AS-PATHs, the router reports a Data Record with a
     basicList composed of (BGP AS-PATH 1, BGP AS-PATH 2, BGP AS-PATH
     3) and the respective Structured Data type semantic of "noneOf".
 
 
     4.4.3. exactlyOneOf
 
     The "exactlyOneOf" Structured Data type semantic specifies that
     only a single element from the Structured Data is an actual
     property of the Data Record.  This is equivalent to a logical XOR
     operation.
 
     For example, if a Flow record contains a basicList of outgoing
     interfaces with the "exactlyOneOf" semantic, then it implies that
     the reported Flow only egressed from a single interface, although
     the Flow Record lists all of the possible outgoing interfaces.
     This is a typical example of a per destination load-balanced Flow
     IPFIX encoding.
 
     For example, a mediator must report an aggregated observation
     point, composed of multiple Template Records:
 
 
         Template Record 1: exporterIPaddress
         This reports a specific exporter
 
         Template Record 2: exporterIPaddress, basicList of interfaces
         This reports a series of interfaces from an exporter
 
         Template Record 3: exporterIPaddress, line card
         This reports a specific line card from an exporter
 
     If these three Template Records are exported with a
     subTemplateMultiList with the semantic "exactlyOneOf", then it
     implies that the Flow Observation Point is reported with the
     values of either Template Record 1, Template Record 2, or Template
 
 
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     Record 3 but not more than one Template Record.
 
 
     4.4.4. oneOrMoreOf
 
     The "oneOrMoreOf" Structured Data type semantic specifies that one
     or more element(s) from the list in the Structured Data is/are
     actual propertie(s) of the Data Record.  This is equivalent to a
     logical OR operation.
 
     For example, a mediator must report an aggregated Flow (for
     example aggregated from IP addresses to IP prefixes), with an
     aggregated observation point, composed of multiple Template
     Records:
 
 
         Template Record 1: exporterIPaddress
         This reports a specific exporter
 
         Template Record 2: exporterIPaddress, basicList of interfaces
         This reports a series of interfaces from an exporter
 
         Template Record 3: exporterIPaddress, line card
         This reports a specific line card from an exporter
 
     If these three Template Records are exported with a
     subTemplateMultiList with the semantic "oneOrMoreOf", then the
     aggregated Flow has been observed on at least one of the
     individual Observation Points reported with the values of a
     specific Template Record, and potentially on multiple Observation
     Points.
 
 
     4.4.5. allOf
 
     The "allOf" structured data type semantic specifies that all of
     the list elements from the Structured Data are actual properties
     of the Data Record.
 
     For example, if a Record contains a basicList of outgoing
     interfaces with the "allOf" semantic, then the observed Flow is
     typically a multicast Flow where each packet in the Flow has been
     replicated to each outgoing interface in the basicList.
 
 
 
 
 
 
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     4.4.6. ordered
 
     The "ordered" Structured Data type semantic specifies that
     elements from the list in the Structured Data are ordered.
 
     For example, an Exporter might want to export the AS10 AS20 AS30
     AS40 BGP AS-PATH.  In such a case, the Exporter would report a
     basicList composed of (AS10, AS20, AS30, AS40) and the respective
     Structured Data type semantic of "ordered".
 
 
     4.5. Encoding of IPFIX Data Types
 
      The following sections define the encoding of the data types
      defined in Section 4.1. above.
 
      When the encoding of a Structured Data Information Element has a
      fixed length (because, for example, it contains the same number of
      fixed-length elements, or if the permutations of elements in the
      list always produces the same total length), the element length
      can be encoded in the corresponding Template Record.  However,
      when representing variable-length data, hierarchical data, and
      repeated data with variable element counts, we RECOMMEND these are
      encoded as a Variable-Length Information Element as described in
      Section 7 of [RFC5101], with the length carried in one or three
      octets before the Structured Data Information Element encoding.
 
 
     4.5.1. basicList
 
      The basicList Information Element defined in Section 4.3.1.
      represents a list of zero or more instances of an Information
      Element and is encoded as follows:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Semantic    |0|          Field ID           |   Element...  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ...Length     |           BasicList Content ...               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
 
 
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                Figure A: basicList Information Element Encoding
 
 
      Semantic
 
          The Semantic indicates the semantic of the list elements,
          i.e., the relationship among the different Information Element
          values within this Structured Data.
 
 
      Field ID
 
          The Field ID is the Information Element identifier of the
          Information Element(s) contained in the list.
 
 
      Element Length
 
          The Element Length indicates the length of each list element
          specified by the Field ID, or contains the value 0xFFFF if the
          length is encoded as a variable-length Information Element at
          the start of the BasicList Content.
 
          The Element Length field is effectively part of a header, so
          even in the case of a zero-element list with no Enterprise
          Number, it MUST NOT be omitted.
 
 
      BasicList Content
 
          A Collection Process decodes list elements from the BasicList
          Content until no further data remains.  A field count is not
          included but can be derived when the Information Element is
          decoded.
 
      Note that in the diagram above, the Field ID is shown with the
      Enterprise bit (most significant bit) set to 0.  If instead the
      Enterprise bit is set to 1, a four-byte Enterprise Number MUST be
      encoded immediately after the Element Length as shown below.  See
      the "Field Specifier Format" section in the IPFIX Protocol
      [RFC5101] for additional information.
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Semantic   |1|         Field ID            |   Element...  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
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      | ...Length     |               Enterprise Number ...           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |              BasicList Content ...            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
              Figure B: basicList Encoding with Enterprise Number
 
 
      Also note that, if a basicList has zero elements, the encoded data
      contains the Semantic, Field ID, the Element Length and the four-
      byte Enterprise Number (if present), while the BasicList Content
      is empty.
 
      If the basicList is encoded as a Variable-Length Information
      Element in less than 255 octets, it is encoded with the Length per
      Section 7 of [RFC5101] as follows:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Length (< 255)|               basicList Content               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      ... continuing as needed                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
        Figure C: Variable-Length basicList Information Element Encoding
                             (Length < 255 octets)
 
 
      If the basicList is encoded as a Variable-Length Information
      Element in 255 or more octets, it is encoded with the Length per
      Section 7 of [RFC5101] as follows:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      |      Length (0 to 65535)      |      ...      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       basicList Content                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
        Figure D: Variable-Length basicList Information Element Encoding
                           (Length 0 to 65535 octets)
 
 
 
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     4.5.2. subTemplateList
 
      The subTemplateList Information Element represents a list of zero
      or more instances of Template data.  Because the Template Record
      referenced by a subTemplateList Information Element can itself
      contain other subTemplateList Information Elements, and because
      these Template Record references are part of the Information
      Elements content in the Data Record, it is possible to represent
      complex hierarchical data structures.  The following diagram shows
      how a subTemplateList Information Element is encoded within a Data
      Record:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Semantic    |         Template ID           |     ...       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                SubTemplateList Content    ...                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
                       Figure E: subTemplateList Encoding
 
 
      Semantic
 
          The Semantic indicates the semantic of the list elements, i.e.
          the relationship among the different Data Records within this
          Structured Data.
 
      Template ID
 
          The Template ID is the ID of the template used to encode and
          decode the SubTemplateList Content.
 
      SubTemplateList Content
 
          The SubTemplateList Content consists of zero or more instances
          of Data Records corresponding to the Template ID.  A
          Collecting Process decodes the Data Records until no further
          data remains.  A record count is not included but can be
          derived when the subTemplateList is decoded.  Encoding and
          decoding are performed recursively if the specified Template
          itself contains Structured Data Information Elements as
          described here.
 
 
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      Note that, if a subTemplateList has zero elements, the encoded
      data contains only the Semantic and the Template ID, while the
      SubTemplateList Content is empty.
 
      If the subTemplateList is encoded as a Variable-Length Information
      Element in less than 255 octets, it is encoded with the Length per
      Section 7 of [RFC5101] as follows:
 
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Length (< 255)|            subTemplateList Content            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    ... continuing as needed                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
         Figure F: Variable-Length subTemplateList Information Element
                         Encoding (Length < 255 octets)
 
 
      If the subTemplateList is encoded as a Variable-Length Information
      Element in 255 or more octets, it is encoded with the Length per
      Section 7 of [RFC5101] as follows:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      |      Length (0 to 65535)      |      ...      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               ...  SubTemplateList Content                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
         Figure G: Variable-Length subTemplateList Information Element
                      Encoding (Length 0 to 65535 octets)
 
 
     4.5.3. subTemplateMultiList
 
      Whereas each top-level element in a subTemplateList Information
      Element corresponds with a single Template ID and therefore has
      the same data type, sometimes it is useful for a list to contain
      elements of more than one data type.  To support this case, each
      top-level element in a subTemplateMultiList Information Element
      carries a Template ID, Length and zero or more Data Records
      corresponding to the Template ID.  The following diagram shows how
 
 
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      a subTemplateMultiList Information Element is encoded within a
      Data Record.  Note that the subTemplateMultiList encoding is
      consistent with Set Header specified in [RFC5101], once the
      Semantic field has been decoded.
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Semantic   |         Template ID X         |Data Records...|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ... Length X  |        Data Record X.1 Content ...            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |        Data Record X.2 Content ...            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |        Data Record X.L Content ...            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |         Template ID Y         |Data Records...|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ... Length Y  |        Data Record  Y.1 Content ...           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |        Data Record Y.2 Content ...            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |        Data Record Y.M Content ...            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |         Template ID Z         |Data Records...|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ... Length Z  |        Data Record Z.1 Content ...            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |        Data Record Z.2 Content ...            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |        Data Record Z.N Content ...            |
 
 
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                              ...                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |
      +-+-+-+-+-+-+-+-+
 
                   Figure H: subTemplateMultiList Encoding
 
      Semantic
 
          The Semantic indicates the top level semantic among Template
          Records, i.e. the relationship among the series of Data
          Records from the different Template Records within this
          Structured Data.
 
          Note: if a semantic is required to describe the relationship
          among the different Data Records corresponding to a single
          Template ID within the subTemplateMultiList, then an encoding
          based on a basicList of subTemplateLists should be used. Refer
          to Section 5.6 for more information.
 
      Template ID
 
          Unlike the subTemplateList Information Element, each list
          element contains a Template ID which specifies the encoding of
          the following Data Records.
 
      Data Records Length
 
          The total length of the Data Records encoding for the Template
          ID previously specified, including the 2 bytes for the
          Template ID and the 2 bytes for the Data Records Length field
          itself.
 
      Data Record X.M
 
          The Data Record X.M consists of the Mth Data Record of the
          Template Record X.  A Collecting Process decodes the Data
          Records until no further data remains, according to the Data
          Records Length.  A record count is not included but can be
          derived when the Element Content is decoded.  Encoding and
          decoding are performed recursively if the specified Template
          itself contains Structured Data Information Elements as
          described here.
 
 
 
 
 
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      In the exceptional case of zero instances in the
      subTemplateMultiList, no data is encoded and the Data Record
      Length is set to zero.
 
      If the subTemplateMultiList is encoded as a Variable-Length
      Information Element in less than 255 octets, it is encoded with
      the Length per Section 7 of [RFC5101] as follows:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Length (< 255)|   subTemplateMultiList Information Element    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      ... continuing as needed                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
      Figure I: Variable-Length subTemplateMultiList Information Element
                        Encoding (Length < 255 octets)
 
 
      If the subTemplateMultiList is encoded as a Variable-Length
      Information Element in 255 or more octets, it is encoded with the
      Length per Section 7 of [RFC5101] as follows:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      |      Length (0 to 65535)      |       IE      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      ... continuing as needed                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
           Figure J: Variable-Length subTemplateMultiList Information
                  Element Encoding (Length 0 to 65535 octets)
 
 
     5. Structured Data Format
 
 
     5.1. Length Encoding Considerations
 
      The new Structured Data Information Elements represent a list that
      potentially carries complex hierarchical and repeated data.  In
      the normal case where the number and length of elements can vary
      from record to record, these Information Elements are encoded as
      variable-length Information Elements as described in Section 7 of
      [RFC5101].
 
 
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      Because of the complex and repeated nature of the data, it is
      potentially difficult for the Exporting Process to efficiently
      know in advance the exact encoding size. As a result, data may be
      recursively encoded starting at a fixed offset, with the final
      length only known and filled in afterwards.
 
      Therefore, the three-byte length encoding is RECOMMENDED for
      variable-length information elements in all Template Records
      containing a Structured Data Information Element, even if the
      encoded length can be less than 255 bytes, because the starting
      offset of the data is known in advance.
 
      An Exporting Process MUST take care when encoding such data to not
      exceed the maximum allowed length of an IPFIX Message, 65535
      bytes, respecting the IPFIX specifications [RFC5101] that imposes:
      "The IPFIX Message Header 16-bit Length field limits the length of
      an IPFIX Message to 65535 octets, including the header".
 
 
     5.2. Recursive Structured Data
 
      It is possible to define recursive relationships between IPFIX
      structured data instances, for example when representing a tree
      structure.  The simplest case of this might be a basicList where
      each element is itself a basicList, or a subTemplateList where one
      of the fields of the referenced template is itself a
      subTemplateList referencing the same Template.  When such a
      recursive relationship exists, variable-length encoding as
      described in Section 7 of [RFC5101] MUST be used.  Also, the
      Exporting Process MUST take care when encoding recursively-defined
      structured data, not to exceed the maximum allowed length of an
      IPFIX Message (as noted in Length Encoding Considerations).
 
 
     5.3. Structured Data Information Elements Applicability in Options
        Template Sets
 
      Structured Data Information Elements MAY be used in Options
      Template Sets.
 
      As an example, consider a mediation function that must aggregate
      Data Records from multiple Observation Point types:
 
         Router 1, (interface 1)
         Router 2, (line card A)
         Router 3, (line card B)
 
 
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         Router 4, (line card C, interface 2)
 
      In order to encode the PSAMP Selection Sequence Report
      Interpretation [RFC5476], the mediation function must express this
      combination of Observation Points as a single new Observation
      Point.  Recall from [RFC5476] that the PSAMP Selection Sequence
      Report Interpretation consists of the following fields:
 
        Scope:     selectionSequenceId
        Non-Scope: one Information Element mapping the Observation Point
                   selectorId (one or more)
 
      Without structured data, there is clearly no way to express the
      complex aggregated Observation Point as "one Information Element
      mapping the Observation Point".  However, the desired result may
      be easily achieved using the structured data types.  Refer to
      Section 8.5. for an encoding example related to this case study.
 
      Regarding the scope in the Options Template Record, the IPFIX
      specification [RFC5101] mentions that "The IPFIX protocol doesn't
      prevent the use of any Information Elements for scope".
      Therefore, a Structured Data Information Element MAY be used as
      scope in an Options Template Set.
 
      Extending the previous example, the mediation function could
      export a given name for this complex aggregated Observation Point:
 
         Scope: Aggregated Observation Point (Structured Data)
         Non-Scope: a new Information Element containing the name
 
 
     5.4. Usage Guidelines for Equivalent Data Representations
 
      Because basicList, subTemplateList, and subTemplateMultiList are
      all lists, in several cases there is more than one way to
      represent what is effectively the same data structure.  However,
      in some cases, one approach has an advantage over the other e.g.
      more compact, uses fewer resources, etc., and is therefore
      preferred over an alternate representation.
 
      A subTemplateList can represent the same simple list of single-
      value Information Elements as a basicList, if the Template
      referenced by the subTemplateList contains only one single-valued
      Information Element.  Although the encoding is more compact than a
      basicList by two bytes, using a subTemplateList in this case
      requires a new Template per Information Element.  The basicList
 
 
 
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      requires no additional Template and is therefore RECOMMENDED in
      this case.
 
      Although a subTemplateMultiList with one Element can represent the
      contents of a subTemplateList, the subTemplateMultiList carries
      two additional bytes (Element Length).  It is also potentially
      useful to a Collecting Process to know in advance that a
      subTemplateList directly indicates that list element types are
      consistent.  The subTemplateList Information Element is therefore
      RECOMMENDED in this case.
 
      The Semantic in a subTemplateMultiList indicates the top level
      semantic among Template Records, i.e. the relationship among the
      series of Data Records from the different Template Records, within
      this Structured Data.  If a semantic is required to describe the
      relationship among the different Data Records corresponding to a
      single Template ID within the subTemplateMultiList, then an
      encoding based on a basicList of subTemplateLists should be used.
 
      Note that the referenced Information Element(s) in the Structured
      Data Information Elements can be taken from the IPFIX information
      model [RFC5102], the PSAMP information model [RFC5477], or any of
      the Information Elements defined in the IANA IPFIX registry [IANA-
      IPFIX].
 
 
     5.5. Padding
 
      The Exporting Process MAY insert some padding octets in structured
      data field values in a Data Record by including the
      'paddingOctets' Information Element as described in [RFC5101]
      Section 3.3.1.  The paddingOctets Information Element can be
      included in a Template Record referenced by Structured Data
      Information Element for this purpose.
 
 
     5.6. Semantic
 
     Semantic interpretations of received Data Records at or beyond the
     Collecting Process remain explicitly undefined, unless that data
     is transmitted using this extension with explicit Structured Data
     type semantic information.
 
     The Exporter SHOULD NOT check all semantically meaningless
     combinations before exporting the Data Record.
 
 
 
 
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     Most forms of Structured Data type semantics are possible, without
     necessarily specifying new semantic values.
 
     For example, the export of the AS10 AS20 AS30 AS40 {AS50,AS60} BGP
     AS-PATH would be reported as a basicList of two elements, each
     element being a basicList of BGP AS, with the top level Structured
     Data type semantic of "ordered".  The first element would contain
     a basicList composed of (AS10,AS20,AS30,AS40) and the respective
     Structured Data type semantic of "ordered", while the second
     element would contain a basicList composed of (AS50, AS60) and the
     respective Structured Data type semantic of "exactlyOneOf".  A
     high level Data Record diagram would be represented as:
 
          (basicList, ordered,
 
              (basicList, ordered, AS10,AS20,AS30,AS40),
 
              (basicList, exactlyOneOf, AS50, AS60)
 
          )
 
     Note that the subTemplateMultiList Structured Data type semantic
     provides the top level semantic among Template Records, i.e. the
     relationship among the series of Data Records from the different
     Template Records within this Structured Data, and not the
     relationships of the different Data Records corresponding to a
     single Template ID within the subTemplateMultiList.  If this is
     required, semantic information needs to be exported for every
     Template ID, in other words a basicList of subTemplateLists should
     be used.
 
     The following case studies show the advantage of a basicList of
     subTemplateLists over a subTemplateMultiList.
 
      Case study 1:
 
     In this example, an Exporter monitoring security attacks must
     export a list of attackers and targets.  For the sake of the
     example, consider attackers A1 or A2 may attack targets T1 and T2.
 
     The first case uses a subTemplateMultiList composed of two
     Template Records, one representing the attacker and one
     representing the target, each of them containing an IP address and
     a port.
 
          Attacker Template Record = (src IP address, src port)
 
 
 
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          Target Template Record = (dst IP address, dst port)
 
     A high level Data Record diagram would be represented as:
 
           (subTemplateMultiList, allOf,
 
              (Attacker Template Record, A1, A2),
 
              (Target Template Record, T1, T2)
 
           )
 
     The Collecting Process can only conclude that all of the attackers
     A1, A2 and the targets T1, T2 are present, without knowing the
     relationship amongst attackers and targets. The Exporting Process
     would have to explicitly call out the relationship amongst
     attackers and targets and the top level semantic offered by the
     subTemplateMultiList isn't sufficient.
 
     The only proper encoding for the previous semantic (i.e. attacker
     A1 or A2 may attack target T1 and T2) uses a basicList of
     subTemplateLists and is represented as follows:
 
          Attacker Template Record = (src IP address, src port)
 
          Target Template Record = (dst IP address, dst port)
 
          (basicList, allof,
 
                (subTemplateList, exactlyOneOf, attacker A1, A2)
 
                (subTemplateList, allOf, target T1, T2)
 
          )
 
 
 
      Case study 2:
 
     In this example, an Exporter monitoring security attacks must
     export a list of attackers and targets.  For the sake of the
     example, attackers A1 or A2 may attack targets T1, attacker A3 is
     attacking targets T2 and T3.  The first case uses a
     subTemplateMultiList composed of two Template Records, one
     representing the attacker and one representing the target, each of
     them containing an IP address and a port.
 
 
 
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          Attacker Template Record = (src IP address, src port)
 
          Target Template Record = (dst IP address, dst port)
 
     A high level Data Record diagram would be represented as:
 
           (subTemplateMultiList, allOf,
 
              (Attacker Template Record, A1, A2, A3),
 
              (Target Template Record, T1, T2, T3)
 
           )
 
     The Collecting Process can only conclude that all of the attackers
     A1, A2, A3 and the targets T1, T2, T3 are present, without knowing
     the relationship amongst attackers and targets.
 
     The second case could use a Data Record definition composed of the
     following:
 
           (subTemplateMultiList, allOf,
 
              (Attacker Template Record, A1, A2),
 
              (Target Template Record, T1),
 
              (Attacker Template Record, A3),
 
              (Target Template Record, T2, T3)
 
           )
 
     With the above representation, the Collecting Process can possibly
     deduce that some relationship exists among (A1, A2, T1) and (A3,
     T2, T3) but cannot understand what it is exactly.  So, there is a
     need for the Exporting Process to explicitly define the
     relationship between the attackers and targets and the top level
     semantic of the subTemplateMultiList is not sufficient.
 
     The only proper encoding for the previous semantic (i.e. attacker
     A1 or A2 attack target T1, attacker A3 attacks targets T2 and T3)
     uses a basicList of subTemplateLists and is represented as
     follows:
 
          Attacker Template Record = (src IP address, src port)
 
 
 
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          Target Template Record = (dst IP address, dst port)
 
          Participant P1:
 
          (basicList, allOf,
 
                (subTemplateList, exactlyOneOf, attacker A1, A2)
 
                (subTemplateList, undefined, target T1)
 
          )
 
          Participant P2:
 
          (basicList, allOf,
 
                (subTemplateList, undefined, attacker A3,
 
                (subTemplateList, allOf, targets T2, T3)
 
          )
 
     The security alert is represented as a subTemplateList of
     participants.
 
          Alert
 
             (subTemplateList, allOf, Participant P1, Participant P2)
 
     Note that, in the particular case of a single element in a
     Structured Data Information Element, the semantic field is
     actually not very useful since it specifies the relationship among
     multiple elements.  Any choice of allOf, exactlyOneOr, or
     OneOrMoreOf would provide the same result semantically.
     Therefore, in case of a single element in a Structured Data
     Information Element, the default "undefined" semantic SHOULD be
     used.
 
 
     6. Template Management
 
      This section introduces some more specific Template Management and
      Template Withdrawal Message-related specifications compared to the
      IPFIX protocol specification [RFC5101].
 
      First of all, the Template ID uniqueness is unchanged compared to
      [RFC5101]; the uniqueness is local to the Transport Session and
 
 
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      Observation Domain that generated the Template ID.  In other
      words, the Set ID used to export the Template Record does not
      influence the Template ID uniqueness.
 
      While [RFC5101] mentions that: "If an Information Element is
      required more than once in a Template, the different occurrences
      of this Information Element SHOULD follow the logical order of
      their treatments by the Metering Process.", this rule MAY not be
      followed for the Structured Data Information Elements.
 
      As specified in [RFC5101], Templates that are not used anymore
      SHOULD be deleted.  Before reusing a Template ID, the Template
      MUST be deleted.  In order to delete an allocated Template, the
      Template is withdrawn through the use of a Template Withdrawal
      Message.
 
 
     7. The Collecting Process's Side
 
      This section introduces some more specific specifications to the
      Collection Process compared to Section 9 in the IPFIX Protocol
      [RFC5101].
 
      As described in [RFC5101], a Collecting Process MUST note the
      Information Element identifier of any Information Element that it
      does not understand and MAY discard that Information Element from
      the Flow Record.  Therefore a Collection Process that does not
      support the extension specified in this document can ignore the
      Structured Data Information Elements in a Data Record, or it can
      ignore Data Records containing these new Structured Data
      Information Elements while continuing to process other Data
      Records.
 
     If the Structured Data contains the "undefined" Structured Data
     type semantic, the Collecting Process MAY attempt to draw its own
     conclusion in terms of the semantic contained in the Data Record,
     exactly as it would have done before the introduction of this
     specification.
 
 
     8. Structured Data Encoding Examples
 
      The following examples are created solely for the purpose of
      illustrating how the extensions proposed in this document are
      encoded.
 
 
 
 
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     8.1. Encoding a Multicast Data Record with BasicList
 
      Consider encoding a multicast Data Record containing the following
     data:
 
      ---------------------------------------------------------------
       Ingress If | Source IP   | Destination IP  | Egress Interfaces
      ---------------------------------------------------------------
            9       192.0.2.201      233.252.0.1         1, 4, 8
      ---------------------------------------------------------------
 
      Template Record for the multicast Flows, with the Template ID 256:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Set ID = 2            |      Length = 24 octets       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID = 256       |       Field Count = 4         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|    ingressInterface = 10    |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|   sourceIPv4Address = 8     |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| DestinationIPv4Address = 12 |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|       basicList = XXX       |     Field Length = 0xFFFF     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
                 Figure K: Encoding basicList, Template Record
 
 
      The list of outgoing interfaces is represented as a basicList with
      semantic allOf, and the Length of the list is chosen to be encoded
      in three bytes even though it may be less than 255 octets.
 
      The Data Set is represented as follows:
 
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Set ID = 256         |          Length = 36          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     ingressInterface = 9                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               sourceIPv4Address = 192.0.2.201                 |
 
 
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             DestinationIPv4Address = 233.252.0.1              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      |        List Length = 17       | semantic=allOf|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | egressInterface FieldId = 14  |egressInterface Field Length=4 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                egressInterface value 1 = 1                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                egressInterface value 2 = 4                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                egressInterface value 3 = 8                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
           Figure L: Encoding basicList, Data Record, Semantic allOf
 
        In the example above, the BasicList contains fixed-length
        elements.  To illustrate how variable-length elements would be
        encoded, the same example is shown below with variable-length
        interface names in the BasicList instead:
 
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Set ID = 256         |          Length = 44          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     ingressInterface = 9                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               sourceIPv4Address = 192.0.2.201                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             DestinationIPv4Address = 233.252.0.1              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      |        List Length = 25       | semantic=allOf|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| InterfaceName FieldId = 82  | InterfaceName Field Len=0xFFFF|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Length = 5   |      'F'      |      'E'      |      '0'      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     '/'       |      '0'      |  Length = 7   |      'F'      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     'E'       |      '1'      |      '0'      |      '/'      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     '1'       |      '0'      |  Length = 5   |      'F'      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     'E'       |      '2'      |     '/'       |      '2'      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
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       Figure M: Encoding basicList, Data Record with Variable-Length
                          Elements, Semantic allOf
 
 
     8.2. Encoding a Load-balanced Data Record with a BasicList
 
      Consider encoding a load-balanced Data Record containing the
      following data:
 
      ---------------------------------------------------------------
       Ingress If | Source IP   | Destination IP  | Egress Interfaces
      ---------------------------------------------------------------
            9       192.0.2.201      233.252.0.1         1, 4, 8
      ---------------------------------------------------------------
 
 
      So the Data Record egressed from either interface 1, 4, or 8.  The
      Data Set is represented as follows:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Set ID = 256         |          Length = 36          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                     ingressInterface = 9                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               sourceIPv4Address = 192.0.2.201                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |             DestinationIPv4Address = 233.252.0.1              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      |        List Length = 17       |sem=exactlyOne |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | egressInterface FieldId = 14  |egressInterface Field Length=4 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                egressInterface value 1 = 1                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                egressInterface value 2 = 4                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                egressInterface value 3 = 8                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
 
 
 
 
 
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        Figure N: Encoding basicList, Data Record, Semantic ExactlyOneOf
 
 
     8.3. Encoding subTemplateList
 
      As explained in Section 3.2. , multiple pairs of
      (observationTimeMicroseconds, digestHashValue) must be collected
      from two different Observation Points to passively compute the
      one-way delay across the network.  This data can be exported with
      an optimized Data Record that consists of the following
      attributes:
 
          5 tuple
                    { observationTimeMicroseconds 1, digestHashValue 1 }
                    { observationTimeMicroseconds 2, digestHashValue 2 }
                    { observationTimeMicroseconds 3, digestHashValue 3 }
                    { ...  , ... }
 
 
      A subTemplateList is best suited for exporting the list of
      (observationTimeMicroseconds, digestHashValue).  For illustration
      purposes, the number of elements in the list is 5; in practice, it
      could be more.
 
      ------------------------------------------------------------------
      srcIP     | dstIP      | src   | dst  |proto| one-way delay
                |            | Port  | Port |     |   metrics
      ------------------------------------------------------------------
      192.0.2.1  192.0.2.105   1025     80     6    Time1, 0x0x91230613
                                                    Time2, 0x0x91230650
                                                    Time3, 0x0x91230725
                                                    Time4, 0x0x91230844
                                                    Time5, 0x0x91230978
      ------------------------------------------------------------------
 
      The following Template is defined for exporting the one-way delay
      metrics:
 
      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Set ID = 2             |      Length = 16 octets       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID = 257       |       Field Count = 2         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
 
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      |0| observationTimeMicroSec=324 |       Field Length = 8        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|   digestHashValue = 326     |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
         Figure O: Encoding subTemplateList, Template for One-Way Delay
                                    Metrics
 
 
      The Template Record for the Optimized Data Record is as follows:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Set ID = 2            |      Length = 32 octets       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID = 258       |       Field Count = 6         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|   sourceIPv4Address = 8     |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| destinationIPv4Address = 12 |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|  sourceTransportPort = 7    |       Field Length = 2        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| destinationTransportPort= 11|       Field Length = 2        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| protocolIdentifier = 4      |       Field Length = 1        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|  subTemplateList = YYY      |     Field Length = 0xFFFF     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
              Figure P: Encoding subTemplateList, Template Record
 
     The list of (observationTimeMicroseconds, digestHashValue) is
     exported as a subTemplateList with semantic allOf.  The Length of
     the subTemplatelist is chosen to be encoded in three bytes even
     though it may be less than 255 octets.
 
     The Data Record is represented as follows:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Set ID = 258          |      Length = 83 octets       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                sourceIPv4Address = 192.0.2.1                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
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      |              destinationIPV4Address = 192.0.2.105             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | sourceTransportPort = 1025    | destinationTransportPort = 80 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Protocol = 6  |      255      | one-way metrics list len = 63 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | semantic=allOf|       TemplateID = 257        | TimeValue1    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 ... octets 2-5 of TimeValue1                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          ... octets 6-8 of TimeValue1         |digestHashVal1=|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                ... 0x0x91230613               | TimeValue2    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 ... octets 2-5 of TimeValue2                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          ... octets 6-8 of TimeValue2         |digestHashVal2=|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                ... 0x0x91230650               | TimeValue3    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 ... octets 2-5 of TimeValue3                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          ... octets 6-8 of TimeValue3         |digestHashVal3=|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                ... 0x0x91230725               | TimeValue4    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 ... octets 2-5 of TimeValue4                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          ... octets 6-8 of TimeValue4         |digestHashVal4=|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                ... 0x0x91230844               | TimeValue5    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 ... octets 2-5 of TimeValue5                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          ... octets 6-8 of TimeValue5         |digestHashVal5=|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                ... 0x0x91230978               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
                   Figure Q: Encoding subTemplateList, Data Set
 
 
 
 
 
 
 
 
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     8.4. Encoding subTemplateMultiList
 
     As explained in Section 4.4.3., a subTemplateMultiList is used to
     export a list of mixed-type content where each top level element
     corresponds to a different Template Record.
 
     To illustrate this, consider the Data Record with the following
     attributes:
 
 
          5 tuple (Flow Keys), octetCount, packetCount
                    attributes for classification
                         selectorId,
                         selectorAlgorithm
                    attributes for sampling
                         selectorId,
                         selectorAlgorithm,
                         samplingPacketInterval,
                         samplingPacketSpace
 
     This example demonstrates that the Selector Report Interpretation
     [RFC5476] can be encoded with the subTemplateMultiList.  More
     specifically, the example describes Property Match Filtering
     Selector Report Interpretation [RFC5476] used for classification
     purposes, and the Systemic Count-Based Sampling as described in
     Section 6.5.2.1 of [RFC5476].  Some traffic will be filtered
     according to match properties configured, some will be sampled,
     some will be filtered and sampled, and some will not be filtered or
     be sampled.
 
     A subTemplateMultiList is best suited for exporting this variable
     data.  A Template is defined for classification attributes and
     another Template is defined for sampling attributes.  A Data Record
     can contain data corresponding to either of the Templates, both of
     them, or neither of them.
 
 
     Consider the example below where the following Data Record contains
     both classification and sampling attributes.
 
     Key attributes of the Data Record:
 
      ------------------------------------------------------------------
      srcIP     | dstIP     | src   | dst  | proto | octetCount | packet
                |           | Port  | Port |       |            | Count
      ------------------------------------------------------------------
      192.0.2.1  192.0.2.105  1025     80      6       108000      120
 
 
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      ------------------------------------------------------------------
 
 
     Classification attributes:
 
      -------------------------------------------
      selectorId  | selectorAlgorithm
      -------------------------------------------
         100         5 (Property Match Filtering)
      -------------------------------------------
 
 
     Sampling attributes:
 
     For Systemic Count-Based Sampling as defined in Section 6.5.2.1 of
     [RFC5476] the required algorithm-specific Information Elements are:
 
           samplingPacketInterval: number of packets selected in a row
           samplingPacketSpace:    number of packets between selections
 
        Example of a simple 1 out-of 100 systematic count-based Selector
        definition, where the samplingPacketInterval is 1 and the
        samplingPacketSpace is 99.
 
      --------------------------------------------------------------
      selectorId | selectorAlgorithm        | sampling | sampling
                 |                          | Packet   | Packet
                 |                          | Interval | Space
      --------------------------------------------------------------
         15        1 (Count-Based Sampling)      1         99
      --------------------------------------------------------------
 
 
     To represent the Data Record, the following Template Records are
     defined:
 
         Template for classification attributes: 259
          Template for sampling attributes: 260
          Template for Flow Record: 261
 
          Flow record (261)
              |  (sourceIPv4Address)
              |  (destinationIPv4Address)
              |  (sourceTransportPort)
              |  (destinationTransportPort)
              |  (protocolIdentifier)
 
 
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              |  (octetTotalCount)
              |  (packetTotalCount)
              |
              +------ classification attributes (259)
              |          (selectorId)
              |          (selectorAlgorithm)
              |
              +------ sampling attributes (260)
              |          (selectorId)
              |          (selectorAlgorithm)
              |          (samplingPacketInterval)
              |          (samplingPacketSpace)
 
 
      The following Template Record is defined for classification
      attributes:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Set ID = 2           |          Length = 16          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Template ID = 259        |        Field Count = 2        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|    selectorId = 302         |        Field Length = 4       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| selectorAlgorithm = 304     |        Field Length = 1       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
            Figure R: Encoding subTemplateMultiList, Template for
                          Classification Attributes
 
      The Template for sampling attributes is defined as follows:
 
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Set ID = 2           |          Length = 24          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Template ID = 260        |        Field Count = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|    selectorId = 302         |        Field Length = 4       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|  selectorAlgorithm = 304    |        Field Length = 1       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| samplingPacketInteval = 305 |        Field Length = 1       |
 
 
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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| samplingPacketSpace = 306   |        Field Length = 1       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
        Figure S: Encoding subTemplateMultiList, Template for Sampling
                                  Attributes
 
 
        Note that while selectorId is defined as unsigned64, it is
        compressed down to 4 octet here as allowed by Reduced Size
        Encoding in Section 6.2 of the IPFIX protocol specifications
        [RFC5101].
 
        Note that while selectorAlgorithm is defined as unsigned16, and
        samplingPacketInterval and samplingPacketSpace are defined as
        unsigned32, they are compressed down to 1 octet here as allowed
        by Reduced Size Encoding in Section 6.2 of the IPFIX protocol
        specifications [RFC5101].
 
 
      Template for the Flow Record is defined as shown below:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Set ID = 2           |          Length = 40          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Template ID = 261        |        Field Count = 8        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|   sourceIPv4Address = 8     |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| destinationIPv4Address = 12 |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| sourceTransportPort = 7     |       Field Length = 2        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| destinationTransportPort=11 |       Field Length = 2        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| protocolIdentifier = 4      |       Field Length = 1        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|   octetTotalCount = 85      |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|   packetTotalCount = 86     |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| subTemplateMultiList = ZZZ  |     Field Length = 0XFFFF     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
      Figure T: Encoding subTemplateMultiList, Template for Flow Record
 
 
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     A subTemplateMultiList with semantic allOf is used to export the
     classification and sampling attributes.  The Length of the
     subTemplateMultilist is chosen to be encoded in three bytes even
     though it may be less than 255 octets.
 
     The Data Record is encoded as follows:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Set ID = 261            |          Length = 49          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 sourceIPv4Address = 192.0.2.1                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              destinationIPv4Address = 192.0.2.105             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  sourceTransportPort = 1025   | destinationTransportPort = 80 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | protocol = 6  |        octetTotalCount = 108000               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     ...       |        packetTotalCount = 120                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     ...       |      255      | Attributes List Length = 21   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |semantic=allOf |   Classif. Template ID = 259  | Classif. Attr |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ...Length = 9 |              selectorId = ...                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ...  100      |selectorAlg = 5|  Sampling Template ID = 260   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Sampling Attributes Length=11 |         selectorId = ...      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  ...         15               |selectorAlg = 1|  Interval = 1 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Space = 99    |
      +-+-+-+-+-+-+-+-+
 
              Figure U: Encoding subTemplateMultiList, Data Set
 
 
     8.5. Encoding an Options Template Set using Structured Data
 
      As described in Section 5.3. , consider a mediation function that
      must aggregate Data Records from multiple different Observation
      Points.
 
 
 
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      Say Observation Point 1 consists of one or more interfaces,
      Observation Points 2 and 3 consist of one or more line cards, and
      Observation Point 4 consists of one or more interfaces and one or
      more line cards.  Without structured data, a template would have
      to be defined for every possible combination to interpret the data
      corresponding to each of the Observation Points.  However, with
      structured data, a basicList can be used to encode the list of
      interfaces and another basicList can be used to encode the list of
      line cards.
 
      For the sake of simplicity, each Observation Point shown below has
      an <interface> or <linecard> or <line card and interface>.  This
      can very well be extended to include a list of interfaces and a
      list of linecards using basicLists as explained above.
 
         Observation Point 1: Router 1, (interface 1)
         Observation Point 2: Router 2, (line card A)
         Observation Point 3: Router 3, (line card B)
         Observation Point 4: Router 4, (line card C, interface 2)
 
 
      The mediation function wishes to express this as a single
      Observation Point, in order to encode the PSAMP Selection Sequence
      Report Interpretation (SSRI).  Recall from [RFC5476] that the
      PSAMP Selection Sequence Report Interpretation consists of the
      following fields:
 
        Scope:     selectionSequenceId
        Non-Scope: one Information Element mapping the Observation Point
                   selectorId (one or more)
 
      For example, the Observation Point detailed above may be encoded
      in a PSAMP Selection Sequence Report Interpretation as shown
      below:
 
       Selection Sequence 7 (Filter->Sampling):
         observation point: subTemplateMultiList.
                              Router 1, (interface 1)
                              Router 2, (line card A)
                              Router 3, (line card B)
                              Router 4, (line card C, interface 2)
         selectorId: 5 (Filter, match IPV4SourceAddress 192.0.2.1)
         selectorId: 10 (Sampler, Random 1 out-of ten)
 
      The following Templates are defined to represent the PSAMP SSRI:
      Template for representing PSAMP SSRI: 262
      Template for representing interface: 263
 
 
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      Template for representing linecard: 264
      Template for representing linecard and interface: 265
 
 
           PSAMP SSRI (262)
              | (SelectionSequenceId)
              |
              +--- Observation Point 1 (263)
              |      (Interface Id)
              |
              +--- Observation Point 2 and 3 (264)
              |      (line card)
              |
              +--- Observation Point 4 (265)
              |      (line card)
              |      (Interface Id)
              |
              | (selectorId 1)
              | (selectorId 2)
 
 
                      Figure V: PSAMP SSRI to be encoded
 
        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          Set ID = 3           |          Length = 26          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Template ID = 262      |         Field Count = 4       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Scope Field Count =  1    |0|  selectionSequenceId = 301  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |       Scope 1 Length = 4      |0| subTemplateMultiList =  ZZZ |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Field Length = 0xFFFF     |0|      selectorId = 302       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Field Length = 4       |0|      selectorId = 302       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Field Length = 4       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
             Figure W: Options Template Record for PSAMP SSRI using
                              subTemplateMultiList
 
      A subTemplateMultiList with semantic allOf is used to encode the
      list of Observation Points.
 
 
 
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        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          Set ID = 2           |          Length = 12          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Template ID = 263      |         Field Count = 1       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |0|   ingressInterface = 10     |        Field Length = 4       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
             Figure X: PSAMP SSRI, Template Record for interface
 
 
        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          Set ID = 2           |          Length = 12          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Template ID = 264      |         Field Count = 1       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |0|      lineCardId = 141       |        Field Length = 4       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
              Figure Y: PSAMP SSRI, Template Record for linecard
 
 
        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          Set ID = 2           |          Length = 16          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Template ID = 265      |         Field Count = 2       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |0|      lineCardId = 141       |        Field Length = 4       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |0|    ingressInterface = 10    |        Field Length = 4       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
       Figure Z: PSAMP SSRI, Template Record for linecard and interface
 
 
      The PSAMP SSRI Data Set is represented as follows:
 
        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |          Set ID = 262         |           Length = 52         |
 
 
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       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                    selectionSequenceId = 7                    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      255      | Observation Point List Len=33 |semantic=allOf |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     OP1 Template ID = 263     |        OP1 Length = 8         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                  OP1 ingressInterface = 1                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |    OP2&3 Template ID = 264    |     OP2&3 Length = 12         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      OP2 lineCardId = A                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      OP3 lineCardId = B                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     OP4 Template ID = 265     |         OP4 Length = 12       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                      OP4 lineCardId = C                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   OP4 ingressInterface = 2                    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         selectorId = 5                        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         selectorId = 10                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
       Figure ZA: Example of a PSAMP SSRI Data Record, Encoded using a
                             subTemplateMultiList
 
      Note that the Data Record above contains multiple instances of
      Template 264 to represent Observation Point 2 (line card A) and
      Observation Point 3 (line card B).  Instead, if a single
      Observation Point had both line card A and line card B, a
      basicList would be used to represent the list of line cards.
 
 
 
     9. Relationship with the Other IFPIX Documents
 
     9.1. Relationship with Reducing Redundancy
 
        "Reducing Redundancy in IP Flow Information Export (IPFIX) and
        Packet Sampling (PSAMP) Reports" [RFC5473] describes a bandwidth
        saving method for exporting Flow or packet information using the
        IP Flow Information eXport (IPFIX) protocol.
 
 
 
 
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        It defines the commonPropertiesID Information Element for
        exporting Common Properties.
 
 
 
     9.1.1. Encoding Structured Data Element using Common Properties.
 
        When Structured Data Information Elements contain repeated
        elements, these elements may be replaced with a
        commonPropertiesID Information Element as specified in
        [RFC5473].  The replaced elements may include the basicList,
        subTemplateList and subTemplateMultiList Information Elements.
 
        This technique might help reducing the bandwidth requirements
        for the export.  However, a detailed analysis of the gain has
        not been done; refer to Section 8.3 of [RFC5473] for further
        considerations.
 
 
 
     9.1.2. Encoding Common Properties elements With Structured Data
        Element.
 
        Structured Data Information Element MAY be used to define a list
        of commonPropertiesID, as a replacement for the specifications
        in [RFC5473].
 
        Indeed, the example in figures 1 and 2 of [RFC5473] can be
        encoded with the specifications in this document.
 
 
           +----------------+-------------+---------------------------+
           | sourceAddressA | sourcePortA |     <Flow1 information>   |
           +----------------+-------------+---------------------------+
           | sourceAddressA | sourcePortA |     <Flow2 information>   |
           +----------------+-------------+---------------------------+
           | sourceAddressA | sourcePortA |     <Flow3 information>   |
           +----------------+-------------+---------------------------+
           | sourceAddressA | sourcePortA |     <Flow4 information>   |
           +----------------+-------------+---------------------------+
           |      ...       |     ...     |            ...            |
           +----------------+-------------+---------------------------+
 
          Figure ZB: Common and Specific Properties Exported Together
                                   [RFC5473]
 
 
 
 
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           +------------------------+-----------------+-------------+
           | index for properties A | sourceAddressA  | sourcePortA |
           +------------------------+-----------------+-------------+
           |          ...           |      ...        |     ...     |
           +------------------------+-----------------+-------------+
 
 
           +------------------------+---------------------------+
           | index for properties A |     <Flow1 information>   |
           +------------------------+---------------------------+
           | index for properties A |     <Flow2 information>   |
           +------------------------+---------------------------+
           | index for properties A |     <Flow3 information>   |
           +------------------------+---------------------------+
           | index for properties A |     <Flow4 information>   |
           +------------------------+---------------------------+
 
         Figure ZC: Common and Specific Properties Exported Separately
                             according to [RFC5473]
 
           +----------------+-------------+---------------------------+
           | sourceAddressA | sourcePortA |     <Flow1 information>   |
           +----------------+-------------+---------------------------+
                                          |     <Flow2 information>   |
                                          +---------------------------+
                                          |     <Flow3 information>   |
                                          +---------------------------+
                                          |     <Flow4 information>   |
                                          +---------------------------+
                                          |            ...            |
                                          +---------------------------+
 
            Figure ZD: Common and Specific Properties Exported with
                      Structured Data Information Element
 
 
        The example in figure ZC could be encoded with a basicList if
        the <Flow information> represents a single Information Element,
        with a subTemplateList if the <Flow information> represents a
        Template Record, or with a subTemplateMultiList if the <Flow
        information> is composed of different Template Records.
 
        Using Structured Data Information Elements as a replacement for
        the techniques specified in "Reducing Redundancy in IP Flow
        Information Export (IPFIX) and Packet Sampling (PSAMP) Reports"
        [RFC5473] offers the advantage that a single Template Record is
        defined.  Hence the Collectors job is simplified in terms of
 
 
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        Template management and combining Template/Options Template
        Records.
 
        However, it must be noted that using Structured Data Information
        Elements as a replacement for the techniques specified in
        "Reducing Redundancy in IP Flow Information Export (IPFIX) and
        Packet Sampling (PSAMP) Reports" only applies to simplified
        cases.  For example, the "Multiple Data Reduction" (Section 7.1
        [RFC5473]) might be too complex to encode with Structured Data
        Information Elements.
 
 
 
     9.2. Relationship with Guidelines for IPFIX Testing
 
        [RFC5471] presents a list of tests for implementers of IP Flow
        Information eXport (IPFIX) compliant Exporting Processes and
        Collecting Processes.
 
        Although [RFC5471] doesn't define any structured data element
        specific tests, the Structured Data Information Elements can be
        used in many of the [RFC5471] tests.
 
        The [RFC5471] series of test could be useful because the
        document specifies that every Information Element type should be
        tested.  However, not all cases from this document are tested in
        [RFC5471].
 
        The following sections are especially noteworthy:
 
          . 3.2.1.  Transmission of Template with fixed size
             Information Elements
 
               - each data type should be used in at least one test.
                  The new data types specified in Section 4.1. should
                  be included in this test.
 
          .  3.2.2. Transmission of Template with variable length
             Information Elements
 
               - this test should be expanded to include Data Records
                  containing variable length basicList,
                  subTemplateList, and subTemplateMultiList Information
                  Elements.
 
          . 3.3.1. Enterprise-specific Information Elements
 
 
 
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               - this test should include the export of basicList,
                  subTemplateList, and subTemplateMultiList Information
                  Elements containing Enterprise-specific Information
                  Elements. e.g., see the example in figure B.
 
          . 3.3.3. Multiple instances of the same Information Element
             in one Template
 
               - this test should verify that multiple instances of the
                  basicList, subTemplateList and subTemplateMultiList
                  Information Elements are accepted.
 
          . 3.5 Stress/Load tests
 
               - since the structured data types defined here allow
                  modeling of complex data structures, they may be
                  useful for stress testing both Exporting Processes
                  and Collecting Processes.
 
 
 
     9.3. Relationship with Bidirectional Flow Export
 
        [RFC5103] describes a method for exporting bidirectional flow
        information, and defines the biflowDirection Information Element
        for this purpose.
 
        [RFC5103] Biflows may be encoded in a subTemplateList or
        subTemplateMultiList. The basicList requires recurrence of a
        single element, so is not suitable for Biflows.
 
        Encoding Biflows with subTemplateList or subTemplateMultiList
        provides a more logical division of the information in both
        directions, although this encoding incurs a small additional
        bandwidth penalty.
 
        An example of Biflow encoding using Structure Data Information
        Elements and comparison with the [RFC5103] Biflow encoding is
        shown in Appendix B.
 
 
     9.4. Relationship with IPFIX Mediation Function
 
        The Structured Data Information Elements would be beneficial for
        the export of aggregated Data Records in mediation function, as
        was demonstrated with the example of the aggregated Observation
        Point in Section 5.3.
 
 
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     10. IANA Considerations
 
      This document specifies several new IPFIX abstract data types, a
      new IPFIX Data Type Semantic, and several new Information
      Elements.
 
      These require the creation of two new IPFIX registries and
      updating the existing IPFIX Information Element registry as
      detailed below.
 
 
     10.1. New Abstract Data Types
 
      Section 4.1. of this document specifies several new IPFIX abstract
      data types.  Per Section 6 of the IPFIX information model
      [RFC5102], new abstract data types can be added to the IPFIX
      information model.  This requires creation of a new IPFIX
      "abstract data types" registry at
      http://www.iana.org/assignments/ipfix.  This registry should
      include all the abstract data types from Section 3.1 of [RFC5102].
 
      Abstract data types to be added to the IPFIX "abstract data types"
      registry are listed below.
 
 
     10.1.1. basicList
 
      The type "basicList" represents a list of any Information Element
      used for single-valued data types.
 
 
     10.1.2. subTemplateList
 
      The type "subTemplateList" represents a list of a structured data
      type, where the data type of each list element is the same and
      corresponds with a single Template Record.
 
 
     10.1.3. subTemplateMultiList
 
      The type "subTemplateMultiList" represents a list of structured
      data types, where the data types of the list elements can be
      different and correspond with different template definitions.
 
 
 
 
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     10.2. New Data Type Semantics
 
     Section 4.2. of this document specifies a new IPFIX Data Type
     Semantic.  Per Section 3.2 of the IPFIX information model
     [RFC5102], new data type semantics can be added to the IPFIX
     information model.  Therefore, the IANA IPFIX
     informationElementSemantics registry [IANA-IPFIX], which contains
     all the data type semantics from Section 3.2 of [RFC5102], must be
     augmented with the "list" value below.
 
 
     10.2.1. list
 
      A list is a structured data type, being composed of a sequence of
      elements e.g. Information Element, Template Record, etc.
 
 
     10.3. New Information Elements
 
      Section 4.3. of this document specifies several new Information
      Elements which are to be created in the IPFIX Information Element
      registry [IANA-IPFIX].
 
      New Information Elements to be added to the IPFIX Information
      Element registry are listed below.
 
      EDITOR'S NOTE: the XML specification in Appendix A must be updated
      with the elementID values allocated below.
 
     10.3.1. basicList
 
      Name: basicList
      Description:
      Specifies a generic Information Element with a basicList abstract
      data type.  For example, a list of port numbers, a list of
      interface indexes, etc.
      Abstract Data Type: basicList
      Data Type Semantics: list
      ElementId: XXX (to be specified by IANA)
      Status: current
 
     10.3.2. subTemplateList
 
      Name: subTemplateList
      Description:
      Specifies a generic Information Element with a subTemplateList
      abstract data type.
 
 
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      Abstract Data Type: subTemplateList
      Data Type Semantics: list
      ElementId: YYY (to be specified by IANA)
      Status: current
 
     10.3.3. subTemplateMultiList
 
      Name: subTemplateMultiList
      Description:
      Specifies a generic Information Element with a
      subTemplateMultiList abstract data type.
      Abstract Data Type: subTemplateMultiList
      Data Type Semantics: list
      ElementId: ZZZ (to be specified by IANA)
      Status: current
 
     10.4. New Structured Data Semantics
 
     Section 4.4. of this document specifies a series of new IPFIX
     structured data type semantics, which is expressed as an 8-bit
     value.  This requires the creation of a new IPFIX "structured data
     types semantics" IPFIX subregistry [IANA-IPFIX].
 
     Entries may be added to this subregistry subject to a Standards
     Action [RFC5226].  Initially, this registry should include all the
     structured data type semantics listed below.
 
 
     10.4.1. undefined
 
      A list is a structured data type, being composed of a sequence of
      elements e.g. Information Element, Template Record, etc.
      Value: 0xFF
      Description: undefined
      Reference: <this future RFC>
 
 
     10.4.2. noneOf
 
      A list is a structured data type, being composed of a sequence of
      elements e.g. Information Element, Template Record, etc.
      Value: 0x00
      Description: noneOf
      Reference: <this future RFC>
 
 
 
 
 
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     10.4.3. exactlyOneOf
 
      A list is a structured data type, being composed of a sequence of
      elements e.g. Information Element, Template Record, etc.
      Value: 0x01
      Description: exactlyOneOf
      Reference: <this future RFC>
 
 
     10.4.4. oneOrMoreOf
 
      A list is a structured data type, being composed of a sequence of
      elements e.g. Information Element, Template Record, etc.
      Value: 0x02
      Description: oneOrMoreOf
      Reference: <this future RFC>
 
     10.4.5. allOf
 
      A list is a structured data type, being composed of a sequence of
      elements e.g. Information Element, Template Record, etc.
      Value: 0x03
      Description: allOf
      Reference: <this future RFC>
 
 
     10.4.6. ordered
 
      A list is a structured data type, being composed of a sequence of
      elements e.g. Information Element, Template Record, etc.
      Value: 0x04
      Description: ordered
      Reference: <this future RFC>
 
 
     11. Security Considerations
 
      The same security considerations as for the IPFIX Protocol
      [RFC5101] apply.
 
 
     12. References
 
     12.1. Normative References
 
        [RFC2119] S. Bradner, Key words for use in RFCs to Indicate
                Requirement Levels, BCP 14, RFC 2119, March 1997.
 
 
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        [RFC5101] Claise, B., Ed., "Specification of the IP Flow
                Information Export (IPFIX) Protocol for the Exchange of
                IP Traffic Flow Information", RFC 5101, January 2008.
 
        [RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and
                J. Meyer, "Information Model for IP Flow Information
                Export", RFC 5102, January 2008.
 
        [RFC5226] T. Narten, T., Alverstrand, H. , "Guidelines for
                Writing an IANA Considerations Section in RFCs",
                RFC5226, May 2008.
 
 
     12.2. Informative References
 
 
        [RFC3917] Quittek, J., Zseby, T., Claise, B., and S. Zander,
                Requirements for IP Flow Information Export, RFC 3917,
                October 2004.
 
        [RFC5103] Trammell, B., and E. Boschi, "Bidirectional Flow
                Export Using IP Flow Information Export (IPFIX)", RFC
                5103, January 2008.
 
        [RFC5470] Sadasivan, G., Brownlee, N., Claise, B., and J.
                Quittek, "Architecture for IP Flow Information Export",
                RFC 5470, March 2009.
 
        [RFC5471] Schmoll, C., Aitken, P., and B. Claise, "Guidelines
                for IP Flow Information Export (IPFIX) Testing", RFC
                5471, March 2009.
 
        [RFC5472] Zseby, T., Boschi, E., Brownlee, N., and B. Claise,
                "IP Flow Information Export (IPFIX) Applicability", RFC
                5472, March 2009.
 
        [RFC5473] Boschi, E., Mark, L., and B. Claise, "Reducing
                Redundancy in IP Flow Information Export (IPFIX) and
                Packet Sampling (PSAMP) Reports", RFC 5473, March 2009.
 
        [RFC5475] Zseby, T., Molina, M., Duffield, N., Niccolini, S.,
                and F. Raspall, "Sampling and Filtering Techniques for
                IP Packet Selection", RFC 5475, March 2009.
 
        [RFC5476] Claise, B., Ed., "Packet Sampling (PSAMP) Protocol
                Specifications", RFC 5476, March 2009.
 
 
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        [RFC5477] Dietz, T., Claise, B., Aitken, P., Dressler, F., and
                G. Carle, "Information Model for Packet Sampling
                Exports", RFC 5477, March 2009.
 
        [IANA-IPFIX] http://www.iana.org/assignments/ipfix/ipfix.xhtml
 
 
     13. Acknowledgement
 
      The authors would like to thank Zhipu Jin, Nagaraj Varadharajan,
      Brian Trammel, and Atsushi Kobayashi for their feedback.
 
 
     14. Authors' Addresses
 
 
      Benoit Claise
      Cisco Systems Inc.
      De Kleetlaan 6a b1
      Diegem 1813
      Belgium
 
      Phone: +32 2 704 5622
      EMail: bclaise@cisco.com
 
 
      Gowri Dhandapani
      Cisco Systems Inc.
      13615 Dulles Technology Drive
      Herndon, Virigina 20171
      United States
 
      Phone: +1 408 853 0480
      EMail: gowri@cisco.com
 
 
      Stan Yates
      Cisco Systems Inc.
      7100-8 Kit Creek Road
      PO Box 14987
      Research Triangle Park
      North Carolina, 27709-4987
      United States
 
      Phone: +1 919 392 8044
      EMail: syates@cisco.com
 
 
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      Paul Aitken
      Cisco Systems (Scotland) Ltd.
      96 Commercial Quay
      Commercial Street
      Edinburgh, EH6 6LX, United Kingdom
 
      Phone: +44 131 561 3616
      EMail: paitken@cisco.com
 
 
 
      Appendix A.  Additions to XML Specification of IPFIX Information
      Elements and Abstract Data Types
 
      This appendix contains additions to the machine-readable
      description of the IPFIX information model coded in XML in
      Appendix A and Appendix B in [RFC5102].  Note that this appendix
      is of informational nature, while the text in section 4.
      (generated from this appendix) is normative.
 
      The following field definitions are appended to the IPFIX
      information model in Appendix A of [RFC5102].
 
         <field name="basicList"
                 dataType="basicList"
                 group="structured-data"
                 dataTypeSemantics="List"
                 elementId="XXX" applicability="all" status="current">
            <description>
              <paragraph>
                 Represents a list of zero or more instances of
                 any single Information Element, primarily used for
                 single-valued data types. For example, a list of port
                 numbers, list of interface indexes, list of AS in a
                 BGP AS-PATH, etc.
              </paragraph>
            </description>
          </field>
 
          <field name="subTemplateList"
                 dataType="subTemplateList"
                 group="structured-data"
                 dataTypeSemantics="List"
                 elementId="XXX" applicability="all" status="current">
            <description>
 
 
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              <paragraph>
                 Represents a list of zero or more instances of a
                 structured data type, where the data type of each list
                 element is the same and corresponds with a single
                 Template Record. For example, a structured data type
                 composed of multiple pairs of ("MPLS label stack entry
                 position", "MPLS label stack value"), a structured data
                 type composed of performance metrics, a structured data
                 type composed of multiple pairs of IP address, etc.
              </paragraph>
            </description>
          </field>
 
          <field name="subTemplateMultiList"
                 dataType="subTemplateMultiList"
                 group="structured-data"
                 dataTypeSemantics="List"
                 elementId="XXX" applicability="all" status="current">
            <description>
              <paragraph>
                Represents a list of zero or more instances of
                structured data types, where the data type of each list
                element can be different and corresponds with
                different template definitions. For example, a
                structured data type composed of multiple access-list
                entries, where entries can be composed of different
                criteria types.
              </paragraph>
            </description>
          </field>
 
 
      The following structured data type semantic definitions are
      appended to the the IPFIX information model in Appendix A of
      [RFC5102].
 
 
        <structuredDataTypeSemantics>
          <structuredDataTypeSemantic name="undefined" value="255">
            <description>
              <paragraph>
                Specifies that the semantic of list elements is not
                specified, and that, if a semantic exists, then it is up
        to
                the Collecting Process to draw its own conclusions.  The
                "undefined" structured data type semantic is the default
                Structured Data type semantic.
 
 
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              </paragraph>
            </description>
          </structuredDataTypeSemantic>
 
          <structuredDataTypeSemantic name="noneOf" value="0">
            <description>
              <paragraph>
                Specifies that none of the elements are actual
        properties
                of the Data Record.
              </paragraph>
            </description>
          </structuredDataTypeSemantic>
 
          <structuredDataTypeSemantic name="exactlyOneOf" value="1">
            <description>
              <paragraph>
                Specifies that only a single element from the
                Structured Data is an actual property of the Data
                Record.  This is equivalent to a logical XOR operation.
              </paragraph>
            </description>
          </structuredDataTypeSemantic>
 
          <structuredDataTypeSemantic name="oneOrMoreOf" value="2">
            <description>
              <paragraph>
                Specifies that one or more element(s) from the list in
                the Structured Data is/are actual propertie(s) of the
                Data Record.  This is equivalent to a logical OR
                operation.
              </paragraph>
            </description>
          </structuredDataTypeSemantic>
 
          <structuredDataTypeSemantic name="allOf" value="3">
            <description>
              <paragraph>
                Specifies that all of the list elements from the
                Structured Data are actual properties of the Data
                Record.
              </paragraph>
            </description>
          </structuredDataTypeSemantic>
 
          <structuredDataTypeSemantic name="ordered" value="4">
            <description>
 
 
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              <paragraph>
                Specifies that elements from the list in the
                Structured Data are ordered.
              </paragraph>
            </description>
          </structuredDataTypeSemantic>
        </structuredDataTypeSemantics>
 
 
      The following schema definitions are appended to the abstract data
      types defined in Appendix B of [RFC5102].
 
 
        <simpleType name="dataType">
          <restriction base="string">
            <enumeration value="basicList">
              <annotation>
                <documentation>
                  Represents a list of zero or more instances of
                  any single Information Element, primarily used for
                  single-valued data types. For example, a list of port
                  numbers, list of interface indexes, list of AS in a
                  BGP AS-PATH, etc.
                </documentation>
              </annotation>
            </enumeration>
            <enumeration value="subTemplateList">
              <annotation>
                <documentation>
                  Represents a list of zero or more instances of a
                  structured data type, where the data type of each list
                  element is the same and corresponds with a single
                  Template Record. For example, a structured data type
                  composed of multiple pairs of ("MPLS label stack entry
                  position", "MPLS label stack value"), a structured
                  data type composed of performance metrics, a
                  structured data type composed of multiple pairs of IP
                  address, etc.
                </documentation>
              </annotation>
            </enumeration>
            <enumeration value="subTemplateMultiList">
              <annotation>
                <documentation>
                  Represents a list of zero or more instances of
                  structured data types, where the data type of each
                  list element can be different and corresponds with
 
 
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                  different template definitions. For example, a
                  structured data type composed of multiple
                  access-list entries, where entries can be
                  composed of different criteria types.
                </documentation>
              </annotation>
            </enumeration>
          </restriction>
        </simpleType>
 
        <simpleType name="dataTypeSemantics">
          <restriction base="string">
            <enumeration value="List">
              <annotation>
                <documentation>
                  Represents an arbitrary-length sequence of structured
                  data elements, either composed of regular Information
                  Elements or composed of data conforming to a Template
                  Record.
                </documentation>
              </annotation>
            </enumeration>
          </restriction>
        </simpleType>
 
        <complexType name="structuredDataTypeSemantics">
          <sequence>
            <element name="structuredDataTypeSemantic"
                     minOccurs="1" maxOccurs="unbounded">
              <complexType>
                <sequence>
                  <element name="description" type="text"/>
                </sequence>
                <attribute name="name" type="string" use="required"/>
                <attribute name="value" type="unsignedByte"
      use="required"/>
              </complexType>
            </element>
          </sequence>
        </complexType>
 
        <element name="structuredDataTypeSemantics"
                 type="structuredDataTypeSemantics">
          <annotation>
            <documentation>
              Structured Data type semantics express the relationship
              among multiple list elements in a Structured Data
 
 
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              Information Element.
            </documentation>
          </annotation>
        </element>
 
 
 
      Appendix B.  Example of Biflow Encoding using Structured Data
      Information Elements
 
        Referring to [RFC5103] figure 1, a Biflow consists of two parts:
        some "key" fields such as src/dst information (IP addresses,
        ports), followed by a set of forward/reverse pairs.
 
        Then looking at [RFC5103] figure 7, we see that the Reverse PEN
        is repeated many times to indicate fields which were observed in
        the reverse direction. Clearly that repetition is wasteful.
 
        Looking back at [RFC5103] figure 1, it's clear that the encoding
        can use a Template Record consisting of the Flow Keys followed
        by a subTemplateList consisting of two elements: one for the
        forward direction, the other for the reverse direction.
 
        The subTemplateList uses a single Template Record to describe
        the fields in both lists since they are a set of forward/reverse
        pairs.
 
 
               Uniflow                             Uniflow
 +-------+-------+-----------------+ +-------+-------+-----------------+
 | src A | dst B | counters/values | | src B | dst A | counters/values |
 +-------+-------+-----------------+ +-------+-------+-----------------+
     |       |            |                             |
     V       V            V                             V
 +-------+-------+---------------------+---------------------+
 | src A | dst B | fwd counters/values | rev counters/values |
 +-------+-------+---------------------+---------------------+
          |                  |                     |
          V                  V                     V
     key fields         fwd element          rev element
 
           Figure B0: Using a subTemplateList to represent a Biflow.
 
      The following example shows the example from Appendix A of
      [RFC5103] encoded using a subTemplateList:
 
 
 
 
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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Set ID = 2           |          Length = 24          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Template ID = 266        |        Field Count = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| flowDirection            61 |       Field Length = 1        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| flowStartSeconds        150 |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| octetTotalCount          85 |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| packetTotalCount         86 |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
                   Figure B1: Template for the Biflow Fields
 
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Set ID = 2           |          Length = 32          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      Template ID = 267        |        Field Count = 6        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| sourceIPv4Address         8 |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| destinationIPv4Address   12 |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| sourceTransportPort       7 |       Field Length = 2        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| destinationTransportPort 11 |       Field Length = 2        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| protocolIdentifier        4 |       Field Length = 1        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|  subTemplateList = YYY      |       Field Length = 29       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
                     Figure B2: Template for the Key Fields
 
      The Template Record includes a subTemplateList with semantic allOf
      for encoding the BiFlow fields for the forward and reverse
      direction.  Note that the subTemplateList is encoded using Fixed
      Length, as shown in the above template definition.
 
 
 
 
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      Also, note that the overall template size is 24 + 32 = 56 octets,
      compared with 64 octets in the [RFC5103] example - so a small
      saving is achieved.
 
 
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Set ID = 267            |          Length = 46          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 sourceIPv4Address = 192.0.2.2                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              destinationIPv4Address = 192.0.2.3               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  sourceTransportPort = 32770  | destinationTransportPort = 80 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | protocol = 6  |semantic=allOf |       Template ID = 266       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | dir = forward |     flowStartSeconds = 2006-02-01 17:00:00    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |           octetTotalCount = 18000             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      |           packetTotalCount = 65               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      ...      | dir = reverse |   flowStartSeconds  = ...     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  ...    2006-02-01 17:00:01   |  octetTotalCount = 128000 ... |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              ...              |   packetTotalCount = 110      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |              ...              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
            Figure B3: Biflow Data Set Encoded using Structured Data
 
 
      Note that the Data Set length is 46, compared with 41 in RFC5103.
      The five additional octets are due to the inclusion of the 8-bit
      semantic, 16-bit Template ID and two, 8-bit direction indicators.
 
      Clearly structured data offers an alternative way to encode
      Biflows.  Although this may not be best suited if the number of
      elements is small as in this example, it does offer a more robust
      and scalable solution if multiple elements need to be encoded.
 
 
 
 
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      Appendix C.  Encoding IPS Alert using Structured Data Information
      Elements
 
      In this section, an IPS alert example is used to demonstrate how
      complex data and multiple levels of hierarchy can be encoded using
      Structured Data Information Elements.  Also, this example
      demonstrates how a basicList of subTemplateLists can be used to
      represent semantics at multiple levels in the hierarchy.
 
      An IPS alert consists of the following mandatory attributes:
      signatureId, protocolIdentifier and riskRating.  It can also
      contain zero or more participants, each participant can contain
      zero or more attackers and zero or more targets.  An attacker
      contains the attributes sourceIPv4Address and applicationId, and
      a target contains the attributes destinationIPv4Address and
      applicationId.
 
      Note that the signatureId and riskRating Information Element
      fields are created for these examples only; the Field IDs are
      shown as N/A.  The signatureId helps to uniquely identify the IPS
      signature that triggered the alert.  The riskRating identifies the
      potential risk, on a scale of 0-100 (100 being most serious), of
      the traffic that triggered the alert.
 
      Consider the example described in case study 2 of Section 5.6. The
      IPS alert contains participants encoded as a subTemplateList with
      semantic allOf.  Each participant uses a basicList of
      subTemplateLists to represent attackers and targets.  For the sake
      of simplicity, the alert has two participants P1 and P2.  In
      participant P1, attacker A1 or A2 attack target T1.  In
      participant P2, attacker A3 attacks targets T2 and T3.
 
     Participant P1:
 
          (basicList, allof,
 
                (subTemplateList, exactlyOneOf, attacker A1, A2)
 
                (subTemplateList, undefined, target T1)
 
          )
 
     Participant P2:
 
          (basicList, allOf,
 
                (subTemplateList, undefined, attacker A3,
 
 
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                (subTemplateList, allOf, targets T2, T3)
 
          )
 
     Alert :
 
             (subTemplateList, allOf, Participant P1, Participant P2)
 
 
      ------------------------------------------------------------------
            |        |        |             participant
      sigId |protocol| risk   |      attacker   |      target
            |   Id   | Rating |    IP   | appId |    IP      | appId
      ------------------------------------------------------------------
      1003     17      10      192.0.2.3  103    192.0.2.103    3001
                               192.0.2.4  104
 
                               192.0.2.5  105    192.0.2.104    4001
                                                 192.0.2.105    5001
      ------------------------------------------------------------------
 
      Participant P1 contains:
      Attacker A1: (IP, appID)=(192.0.2.3, 103)
      Attacker A2: (IP, appID)=(192.0.2.4, 104)
      Target T1: (IP, appID)= (192.0.2.103, 3001)
 
      Participant P2 contains:
      Attacker A3: (IP, appID) = (192.0.2.5, 105)
      Target T2: (IP, appID)= (192.0.2.104, 4001)
      Target T3: (IP, appID)= (192.0.2.105, 5001)
 
 
      To represent an alert, the following Templates are defined:
      Template for target (268)
      Template for attacker (269)
      Template for participant (270)
      Template for alert (271)
 
           alert (271)
           |  (signatureId)
           |  (protocolIdentifier)
           |  (riskRating)
           |
           +------- participant (270)
                    |
                    +------- attacker (269)
                    |           (sourceIPv4Address)
 
 
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                    |           (applicationId)
                    |
                    +------- target (268)
                             |  (destinationIPv4Address)
                             |  (applicationId)
 
      Note that the attackers are always composed of a single
      applicationId, while the targets typically have multiple
      applicationId, for the sake of simplicity this example shows only
      one applicationId in the target.
 
      Template Record for target, with the Template ID 268:
 
      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Set ID = 2             |      Length = 16 octets       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID = 268       |       Field Count = 2         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0| destinationIPv4Address = 12 |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|       applicationId = 95    |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
               Figure C0: Encoding IPS Alert, Template for Target
 
 
      Template Record for attacker, with the Template ID 269:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Set ID = 2            |      Length = 16 octets       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID = 269       |       Field Count = 2         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|    sourceIPv4Address = 8    |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|     applicationId = 95      |       Field Length = 4        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
              Figure C1: Encoding IPS Alert, Template for Attacker
 
 
      Template Record for participant, with the Template ID 270:
 
 
 
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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Set ID = 2            |      Length = 12 octets       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID = 270       |       Field Count = 1         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|       basicList = XXX       |     Field Length = 0xFFFF     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
            Figure C2: Encoding IPS Alert, Template for Participant
 
 
      The Template Record for the participant has one basicList
      Information Element, which is a list of subTemplateLists of
      attackers and targets.
 
      Template Record for IPS alert, with the Template ID 271:
 
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Set ID = 2            |      Length = 24 octets       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Template ID = 271       |       Field Count = 4         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|    signatureId = N/A        |       Field Length = 2        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|   protocolIdentifier = 4    |       Field Length = 1        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|     riskRating = N/A        |       Field Length = 1        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |0|     subTemplateList = YYY   |     Field Length = 0xFFFF     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
             Figure C3: Encoding IPS Alert, Template for IPS Alert
 
      The subTemplateList in the alert Template Record contains a list
      of participants.
 
      The Length of basicList and subTemplateList are encoded in three
      bytes even though they may be less than 255 octets.
 
 
      The Data Set is represented as follows:
 
 
 
 
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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Set ID = 271         |         Length = 102          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      signatureId = 1003       | protocolId=17 | riskRating=10 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      |participant List Length  = 91  |semantic=allOf |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | participant Template ID = 270 |     255       | P1 List Len = |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      41       | semantic=allOf|    P1 List Field ID = YYY     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | P1 List Field ID Len = 0xFFFF |      255      |P1 attacker ...|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | List Len = 19 |sem=exactlyOne | P1 attacker Template ID = 269 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          P1 attacker A1 sourceIPv4Address = 192.0.2.3         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               P1 attacker A1 applicationId = 103              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          P1 attacker A2 sourceIPv4Address = 192.0.2.4         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               P1 attacker A2 applicationId = 104              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      | P1 target List Len = 11       | sem=undefined |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  P1 target Template ID = 268  | P1 target T1 destinationIPv4  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ... Address = 192.0.2.103     |P1 target T1 applicationId =...|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ...       3001                |      255      | P2 List Len = |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ...  41       | semantic=allOf|    P2 List Field ID = YYY     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | P2 List Field ID Len = 0xFFFF |      255      |P2 attacker ...|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | List Len = 11 | sem=undefined | P2 attacker Template ID = 269 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          P2 attacker A3 sourceIPv4Address = 192.0.2.5         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               P2 attacker A3 applicationId = 105              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |      255      |    P2 target List Len = 19    |semantic=allOf |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  P2 target Template ID = 268  | P2 target T2 destinationIPv4  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
 
     <Claise, et. Al>       Expires January 10 2011          [Page 71]
 

     Internet-Draft  <Export of Structured Data in IPFIX>  July 2010
 
 
      | ... Address = 192.0.2.104     |P2 target T2 applicationId =...|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ...       4001                | P2 target T3 destinationIPv4  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ... Address = 192.0.2.105     |P2 target T3 applicationId =...|
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | ...       5001                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 
                    Figure C4: Encoding IPS Alert, Data Set
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
     <Claise, et. Al>       Expires January 10 2011          [Page 72]
 

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